Homework Help:
Two Slit Interference

1. The problem statement, all variables and given/known data
An optical two-slit experiment is setup with its slits separated by 40 X 10-3 cm and produces a second order maximum at an angle of 0.09 degrees. What would the wavelength of the light need to be if we kept the position of the second order maximum the same, but increased the slit separation of 63 X 10-3 cm?

2. Relevant equations
wsinϑ=mλ

3. The attempt at a solution
630000nm*sin0.09=2λ
λ=494.8nm

I'm almost positive that this is right, but the system won't accept my answer. Please help me!